1.前言

今天简单展示一个归并排序解题，难度简单。

2.题目简介

题目链接：LINK

3.求解思路

4.示例代码

//归并排序
class Solution {
public:
    vector<int> tmp;
    vector<int> sortArray(vector<int>& nums) {
        tmp.resize(nums.size());

        mergeSort(nums, 0, nums.size() - 1);
        return nums;
    }

    void mergeSort(vector<int>& nums, int begin, int end)
    {
        if(begin >= end) return;

        //1.找中间点
        int mid = (begin + end) >> 1;
        //此时被划分为了两部分：[begin, mid] [mid+1, end]

        //2.递归
        mergeSort(nums, begin, mid);
        mergeSort(nums, mid + 1, end);

        //3.回归
        int cur1 = begin, cur2 = mid + 1, i = begin;
        while(cur1 <= mid && cur2 <= end)
        {
            tmp[i++] = nums[cur1] >= nums[cur2] ? nums[cur2++] : nums[cur1++];
        }
        while(cur1 <= mid) tmp[i++] = nums[cur1++];
        while(cur2 <= end) tmp[i++] = nums[cur2++];
        //拷回原来的数组
        for(int i = 0; i < end - begin + 1; i++)
        {
            nums[begin + i] = tmp[begin + i];
        }
    }
};

EOF